The Duke of Cambridge joined tennis greats and other celebrities at the winter wonderland-themed event

William spoke to guests who had travelled all the way from the U.S. to attend the star-studded gala

The Duke and Duchess of Cambridge delighted the world this week when they announced that Kate was pregnant.

The
couple were forced to announce the eagerly-awaited news after Kate was
admitted to King Edward VII Hospital in London on Monday after she fell
ill at her parents' house in Bucklebury, Berkshire.

She was put on a drip and spent three nights in hospital.

Kate returned to Nottingham Cottage in the grounds of Kensington Palace and cancelled upcoming engagements to rest.

Prince William talks to tennis players Novak Djokovic, left, and John McEnroe, right, during the gala

Sadie Frost arrives at the charity event at the Royal Albert Hall against the winter wonderland backdrop

The Duchess of Cambridge's
recuperation will no doubt be tinged by sadness after it emerged that
nurse Jacintha Saldanha died in a suspected suicide.

Mrs Saldanha was found dead at King Edward VII hospital's staff lodgings.

Only three days before her death, the
46-year-old nurse had transferred a hoax call from two Australian DJs
who obtained intimate details about the Duchess of Cambridge while she
was staying at the hospital.

The Duke greets people from the homeless charity Centrepoint, of which he is patron, at the Royal Albert Hall

Prince William is to spend this evening with the pregnant Duchess who is recuperating after spending three nights in hospital with severe morning sickness